Several coupling devices for coiled tubing are known. The coupling devices generally comprise a male and a female part, of which the male part can be fastened at the end of a coiled tubing and the female part can be arranged as a part of a bottom-hole equipment that can be brought down with the coiled tubing.
When joining the coupling parts on deck it will, because of high stiffness of the coiled tubing, be difficult to position the coiled tubing correctly, for which reason the coupling parts are designed for simple alignment into position for joining. The units can also be joined within a well bore, as one coupling part is brought down into the well on the end of a coiled tubing for joining with the other coupling part that previously has been arranged in the well bore.
Examples of coupling devices of the above-mentioned types are described in the U.S. Pat. Nos. 6,460,900, 6,450,541, 5,787,982, 6,209,652, 6,439,305 and 6,698,514, to which publications reference is made.
None of the above-mentioned patent applications describes a coupling device comprising a verifying device that can verify whether the coupling and locking are correct. Neither are any coupling devices described that locks automatically by joining of the coupling parts, whereby connection and disconnection take place at the same position in the working string, without any further manipulation than joining the coupling parts. There is a demand for a coupling device for coiled tubing, which coupling device locks automatically when joining the coupling parts. There is also a demand for a coupling device with a verifying device that immediately after joining can verify correct locking.
In patent publication EP 0298683 B1 a down-hole lock assembly with a verifying device that can verify whether the coupling is correct or not, is described. However, the verification cannot be made until after one of the coupling parts, the so-called running tool (11) has been disconnected from the lower coupling part (12), the lock mandrel body. Said coupling device is relatively complicated and will not be locked automatically by simple joining of the coupling parts.
More specifically, patent publication EP 0298683 B1 describes a down-hole lock assembly comprising a lock mandrel (10) connected to a running tool (11) which holds an inner mandrel (13) located within a body (12) of the lock mandrel (10) in a position which allows lock-out keys (20) of the lock mandrel (10) to remain within the outside diameter of the lock mandrel body (12), shear pins (34) adapted on downward jarring against a landing nipple to expand the keys (20) and shear pins (33) adapted on upward jarring to release the running tool (11), said running tool (11) having a tell-tale device (30) to indicate that the lock mandrel (10) is correctly set in the landing nipple, the inner mandrel (13) being resiliently urged in an upward direction, i.e. in the direction of the flow from the well, to activate the lock-out keys (20) to set the lock, and latch means (22) being provided to hold the inner mandrel (13) in a downward disposition against its resilient means prior to setting the lock, distinguished in that the running tool (11) carries a tell-tale collet means (30) connected thereto by a shear pin (32), said collet means being adapted when the running tool (11) is released from the lock mandrel after setting the lock to disengage intact from the lock mandrel (10) if the lock-out keys (20) are correctly set and to foul the inner mandrel (13) and shear the shear pin (32) if the lock-out keys (20) are incorrectly set, said collet means being adapted to remain on said running tool (11) and be withdrawn with said running tool (11) when said running tool (11) is released from said mandrel (10) when said lock-out keys (20) are correctly set and also when said lock-out keys (20) are incorrectly set. The latch means (22) comprises longitudinally extending finger means (22) on the external face of the inner mandrel, biased laterally inwards but for location in the groove means (24, 25) in the inner face of the main body (12) at correct alignment for locking. Also the collet means on the running tool comprises a plurality of longitudinally extending fingers adapted to pass upwardly through the inner mandrel undamaged if the finger means of the latch are located in the upper groove of the main body and to strike said finger means if said finger means are not so located out of the path of the collet means, which means if the locking is not successful.
There is a demand for a simpler coupling device without the above-mentioned deficiencies.